What does search and rescue teams spay paint on building walls mean?

In the wake of hurricanes Harvey and Irma, Urban Search and Rescue (US&R) teams have been assessing damaged buildings. Their task is to locate survivors and also to find the remains of folks killed in the storm.

During the search process, US&R teams will make spray paint marks on buildings. These markings communicate messages to other teams. These markings can also be a safety net alerting that a team is in trouble.

Upon entering a structure a team will make a slash mark going down from left to right. This mark signals someone is in the building. Above the mark, the date and time the team enters will be listed. To the left of the mark will be the team name.

The below example shows Wisconsin Task Force team one entered a building on September 12, 2017, at about 9:30 am.

After the teams exit the building they put a second slash mark to create an X. This signals to other teams the building search has been completed. If a team noticed only one slash with a long period of time with out anyone exciting it can be a sign the folks inside are in trouble.

At the bottom of the X a list of people in the structure will be listed. Often times it is something simple like “2 live” meaning two people who are okay. Or it could be 1 DOA, meaning one person who was Dead on Arrival of rescue teams. If there is a mix of people alive and dead then one number is placed over another.

The below example shows that the team exited the building after finding two alive and one dead. In a perfect world when folks are found alive they would be educated right away. However, there are times the living need to continue to shelter in place. Evacuation teams might follow the US&R teams to remove the survivors.

Then on the right side of the X, any possible hazards will be listed. Hazards could include standing water, wild animal infestation, gas leaks, or biological hazards of advance decomposition. The below example shows a team completed a search finding a body and indicating it was still flooded with rats inside.

If the X is outlined in a box that is an indicator telling other teams to keep out. Often it indicates massive structural damage. Other specialized responders will be needed to shore the building to prevent collapse.

There are some more advanced markings also used. For the average author looking to add something to a novel, this is more than enough.